Method and system for manufacturing a molded body

ABSTRACT

A method and system for fabricating molded components which include a molded body and a plurality of electrically conductive leads protruding therefrom. These components are made by overlaying an anode lead frame having anode leads, on a cathode lead frame having cathode leads, and then depositing molding material on intersected anode and cathode leads. The molded components are manufactured in an assembly line process which includes a feeder to feed the anode and cathode lead frames and a molder to deposit the molding material. Preferably, these molded components are lamp tiles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.09/559,545, filed Apr. 28, 2000, now U.S. Pat. No. 6,022,915, which is adivisional application of U.S. application Ser. No. 09/172,760, filedOct. 15, 1998, now U.S. patent 6,087,195.

FIELD OF THE INVENTION

This invention relates to an automated manufacturing of lamp tiles and,more specifically, to manufacturing of the lamp tiles from a pluralityof lead frame reels in an assembly line process.

BACKGROUND OF THE INVENTION

Small light lamps such as light emitting diodes (LEDs) have been widelyused as indicators or components of displays because of their highmechanical stability, low operating voltage, and long service life. Whena plurality of the small light lamps are arranged in a two dimensionalarray and inserted into an electrically wired board configured tocontrol each lamp, the resulting structure forms a large display board.In one prior system, such large display boards have been employed asscore boards in sports arenas.

Manufacturing of display boards requires wiring of internal electricalcircuit for controlling each lamp and wiring sockets for receiving eachlamp. The laps also must be individually inserted into the sockets. Thepreceding requirements, among others, make the manufacturing of displayboards to be cumbersome and not readily adaptable to an automatedassembly line processing. In turn, the display boards are ordinarilycustom designed with high manufacturing costs.

SUMMARY OF THE INVENTION

The present invention is preferably directed to a method and apparatusfor manufacturing lamp tiles. A lamp tile is a panel which has aplurality of light openings into which small light lamps are insertedand which includes a plurality of anode and cathode leads electricallyconnected to anode and cathode ends of corresponding small lamps forsupplying or cutting off electrical power to the lamps. The lamp tilesare mounted into a display board configured to receive the anode andcathode leads of the lamp tiles. Such a display board also includescontrol circuit to control the on/off states of each lamp of the lamptiles.

By using the present invention, the manufacturing process of displayboards is simplified by bypassing, among other things, the requirementof wiring individual sockets to receive each lamp into the display boardbecause lamps are already mounted in the lamp tiles. Furthermore, sincelamp tiles have standard sizes and since the lead frames are designedsuch that they are adopted to be mass produced, the lamp tiles areproduced in an assembly line. These and other advantages provided inthis invention reduces the overall costs of manufacturing the displayboards.

Specifically, the present invention relates to a method for fabricatingat least one lamp tile having a molded body and a plurality ofelectrically conductive leads protruding therefrom, by providing a firstlead frame segment defining a first aperture and including at least onefirst lead extending into the first lead frame aperture; providing asecond lead frame segment defining a second aperture and including atleast one second lead extending into the second lead frame aperture;overlaying the first and second lead frame segments above the other suchthat the first and second leads form an intersection in a plan view ofthe overlaid lead frame segments, and the first and second leads arespaced apart from each other at the intersection by a predetermineddistance in a side view of the overlaid lead frame segments; anddepositing molding material in a predetermined pattern on theintersection, thereby forming the molded body wherein a portion of thefirst lead protrudes from the deposited molding material, and a portionof the second lead protrudes from the deposited molding material.

This method includes forming a light opening over the intersectionexposing portions of the first and second leads and trimming the firstand second leads from the first and second lead frame segments. The stepof overlaying the first and second leads includes the step of settingthe predetermined distance to be between 0.01 and 0.03 inches, andpreferably, between 0.01 and 0.015 inches, and the step of depositingthe molding material includes the step of selecting the molding materialto be a heat treatable nylon which is heat treatable at a temperature ofat least 300° C.

Preferably, the first frames segment are produced by the step ofstamping the first lead frame segments on a first elongated sheet madeof electrically conductive rigid material, and the second frame segmentsare made by the step of stamping the second lead frame segments on asecond elongated sheet made of electrically conductive rigid material.The method preferably includes the step of depositing epoxy materialbetween first and second leads over the intersections.

The invention also relates to a system for fabricating a plurality oflamp tiles, comprising a plurality of first lead frame segments whichdefine first apertures and include a plurality of first leads extendinginto the first lead frame apertures; a plurality of second lead framesegments which define second apertures and including a plurality ofsecond leads extending into the second lead frame apertures; a pluralityof pins configured to overlay one of the first and second lead framesegments; a feeder for receiving the plurality of first and second leadframe segments and for overlaying the plurality of pins on one of thefirst and second lead frame segments such that corresponding the firstand second leads form an array of intersections in a plan view of theoverlaid lead frame segments, and are spaced apart from each other ateach intersection by a predetermined distance in a side view of theoverlaid lead frame segments; and a molder configured to deposit moldingmaterial in a predetermined pattern on a plurality of the intersectionssuch that a portion of each corresponding the first lead protrudes fromthe deposited molding material, and a portion of each corresponding thesecond lead protrudes from the deposited molding material.

The system preferably includes a trimmer configured to cut the first andsecond leads from the first and second lead frame segments, a firststamping device configured to stamp the first lead frame segments on afirst elongated sheet made of electrically conductive rigid material,and a second stamping device configured to stamp the second lead framesegments on a second elongated sheet made of electrically conductiverigid material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a portion of a cathode lead frame, whichincludes three lead frame segments of the cathode lead frame;

FIG. 2 is a plan view of a portion of an anode lead frame, whichincludes four lead frame segments of the anode lead frame;

FIG. 3 is an overview of an automated assembly line for manufacturinglamp tiles;

FIG. 4 is a plan view of one set of anode leads overlaid on top of oneset of cathode leads;

FIG. 5 is a side view of an anode lead frame overlaid on top of acathode lead frame;

FIG. 6 is a plan view of molded lamp tiles; and

FIG. 7 is a cross-sectional view of a light opening.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a cathode lead frame 101 includes a plurality oflead frame segments 103. Each lead frame segment 103, in turn, has acathode lead aperture 105 delineated by side portions which include apair of side rails 107 and crossbars 109. The pair of spaced apart siderails 107 are connected to and supported by the crossbars 109. Cathodefeeder holes 111, regularly spaced, are formed in the side rails 107,and cathode lead alignment holes 113 are formed in the crossbars 109.Each cathode lead frame segment 103 also includes a plurality of cathodeleads 117 attached to the side portions and extending into the cathodelead aperture 105. Blackened portions in FIG. 1 illustrate two sets ofcathode leads 125.

The cathode lead frame 101 is made substantially from copper. Anyelectrically conductive rigid material, however, is adequate for makingthe cathode lead frame 101. The rigid material is formed into anelongated sheet which is, then, nickel plated. The thickness of theelongated sheet is on the range of {fraction (5-20/1,000)} inches and,preferably, {fraction (10-15/1,000)} inches. The nickel plated sheet, inturn, is preferably gold plated. In other embodiments, the nickel platedsheet is plated with palladium, silver or any electrically conductiveprecious metal.

The cathode lead frame segments 103 are formed in the elongated sheet,preferably, by a stamping process and, alternatively, by an etchingprocess, both of which are known processes in the art. The elongatedsheet is sufficiently lengthy to form at least a thousand lead framesegments and, preferably, more than five thousand lead segments.

In one aspect of the preferred embodiment, the cathode lead frameaperture 105 has a substantially rectangular shape. In alternativeembodiments, the cathode lead frame aperture 105 is a square, circle orany shape that allows formation of a plurality of cathode leads.

In another aspect of the preferred embodiment, each cathode lead 117 hastwo lead ends 115. One of the lead ends 115 is attached to the siderails 107 and the other is attached to respective connecting members123. The connecting members 123 are provided to render support betweenthe two different sets of cathode leads 125 which eventually becomeparts of two lamp tiles. In other words, two lamp tiles are formed fromeach cathode lead frame segment 103. In other embodiments, variousnumbers of sets of cathode leads are provided, such as four sets in atwo by two array, six sets in a three by two array, or eight in a fourby two array. In these embodiments, however, the number of sets ofcathode leads provided in a cathode lead frame segment is limited sincestringing too many of them together by connecting members would notmaintain structural integrity of the cathode lead frame.

In yet another aspect of the preferred embodiment, each set of cathodeleads 125 includes four cathode leads 117, each cathode lead 117including four bubble shaped nodes 119 arranged to form four arrays ofneighboring nodes 121. Each node 119 comes in contact with a cathode endof a lamp, as will be discussed later. The bubble shape is provided forgood electrical contact between it and the cathode end of a lamp. Inalternative embodiment, nodes with different shapes are provided and theonly requirement on the shape of the nodes is that they provide goodcontacts to respective cathode ends of lamps. In one alternativeembodiment, a small depression or bump is formed in each of the nodes inorder to achieve a good contact with a cathode end.

In other alternative embodiments, different number of cathode leads 117are provided for each set of cathode leads 125, and different number ofnodes 119 are provided for each cathode leads 117. In one exemplaryembodiment, six cathode leads for each set of cathode leads and sixnodes for each cathode lead are provided. In another exemplaryembodiment, four cathode leads for each set of cathode leads and sixnodes for each cathode lead are provided. As the preceding exemplaryembodiments illustrate, the number of cathode leads in a set of cathodeleads and the number of nodes for each cathode lead are not limited to afour by four array as shown in FIG. 1.

Now referring to FIG. 2, an anode lead frame 201 includes a plurality ofanode lead frame segments 203. Each anode lead frame segment 203includes anode crosspieces 205, which delineates individual lead frameaperture 207. Each anode crosspiece 205 includes anode alignment holes209. In addition, each anode lead frame segment 203 includes a pluralityof anode leads 211. Each anode lead 211 in turn has two anode lead ends213 one of which is connected to the anode crosspieces 205 and the otherone of which is connected to connecting members 215. Two neighboringanode leads form a pair of anode leads 217. Each set of anode leads 219includes four pairs of anode leads 217 corresponding to the four arraysof neighboring nodes 121 of each set of cathode leads 125 in FIG. 1.

In one aspect of the preferred embodiment, the anode lead frame is madefrom substantially the same material and by substantially the sameprocess as that of the cathode lead frame 101. In an alternativeembodiment, the anode lead frame is made from different electricallyconductive rigid material or made by a different process than that ofthe cathode lead. In addition, other alternative embodiments inconnection with the number of anode lead frames, the shape of anodeaperture, the number of sets of anode leads per anode lead framesegment, the number of pairs of anode leads per anode set of anodeleads, and the shape of anode leads have similar options available tothem as that of cathode lead frame 101 and its corresponding parts.

In another aspect of the preferred embodiment, no side rail similar tothe cathode side rails 107 is provided to the anode lead frame. Inalternative embodiments, side rails are provided to enhance thestructural integrity of the anode lead frame 201.

Referring to FIG. 4, in a plan view, when the anode alignment holes 209arc co-located with the alignment holes 113 in the cathode lead frame101, each pair of anode leads 217 intersect with corresponding array ofnodes 121 of the cathode lead frame 101. This arrangement allowsindividualized control of lamps in contact with each node of the cathodeleads and anode leads as discussed later in more detail.

The intersections between the cathode and anode leads 117, 211 form atwo dimensional array. More specifically, the anode and cathodes leads117, 211 perpendicularly intersect with each other. In alternativeembodiments, the anode and cathode leads do not cross each otherperpendicularly. Instead, the anode and cathode leads intersect eachother in an angle other than 90 degrees. In these alternativeembodiments, the cathode leads or anode leads extend at an angle intothe cathode lead frame aperture and the anode lead frame aperture,respectively. These alternative embodiments are possible as long asindividual control of the light lamps can be performed which will bediscussed later.

Now referring FIG. 3, a manufacturing assembly line 301 includes ananode lead frame 201, a cathode lead frame 101, a feeder 307, a molder309, a trimmer 311 and a post processor 313. The feeder 307 has aplurality of cathode feed pins 315, a plurality of alignment pins 317and a plurality of precision positioning pins 319. In an alternativeembodiment, two stamping devices are provided (not shown in FIG. 3) forstamping cathode and anode lead frames in two elongated sheets of metal.

The anode lead frame 201 is rolled up into a anode reel, and the cathodelead frame 101 is rolled up into a cathode reel. The anode and cathodereels are unrolled to feed their respective lead frames into the feeder307.

The cathode feeder pins 315, configured to fit into the feeder holes 111in the cathode lead frame 101, are inserted into the feeder holes 111.Subsequently, the alignment pins 317, configured to fit into thealignment holes 113 in the cathode lead frame 101 and fit into the anodealignment holes 209 in the anode lead frame 201, are inserted into thealignment holes 113, 209. Once the alignment pins are fitted into thealignment holes 113, 209, the cathode lead frame 101 and anode leadframe 201 are overlaid and aligned. The combination of the cathodefeeder pins 315 and the alignment pins 317 move the cathode and anodereels 101, 201 along the assembly line 301.

In alternative embodiments, the cathode lead frame holes and the cathodealignment holes and the anode alignment holes are not provided. In theseembodiments, the cathode feeder pins 315 and the alignment pins 317 feedand align the cathode and anode lead frames 101, 201 by using side rails107, crossbars 109 and crosspieces 205.

The precision positioning pins 319 place the anode lead frame 201 apartfrom the cathode reel 101 by a distance on the range of {fraction(10-30/1,000)} inches, and, preferably, on the range of {fraction(10-15/1,000)} inches. The distance is designated as D in FIG. 5. In anyevent, the minimum distance is electrical conductivity between the anodeand cathode leads, and the maximum distance is controlled by the lampdesign. For example, if the distance between the anode and cathode leadsis too large than the cathode and anodes of lamps may not be connectedto the cathode and anode leads efficiently.

The distance between the cathode lead frame 101 and the anode lead frame201 is maintained when they are fed into the molder 309. The molder 309then deposits molding material onto the respective lead frame portionsof the cathode reel 101 and anode reel 201 in a predefined pattern. Themolding material is a high temperature nylon and is, preferably, Amodel®resin, a product manufactured by Amoco. Amodel® resin is a hightemperature nylon which can withstand up to 570° F. without beingdeformed. However, any other material which can be molded and has hightemperature tolerance is adequate.

In one aspect of the preferred embodiment, the molding material isdeposited between the anode and cathode leads where they intersect withother. In an alternative embodiment, some potting material such as epoxymaterial is deposited between the anode and cathode leads where they areat the intersections. This alternative embodiment enhances the bondingbetween the anode and cathode leads and, depending on the material used,may reduce the occurrences of shorting between the anode and cathodeleads.

Referring to FIG. 6, in the molder 309 each lamp tile 601 is formedwithin the predefined pattern. The predefined pattern includes a set ofdam-bars 607 and gate trims 605 and a set of cylindrically shaped cores(not shown) placed where light openings 603, also referred as lightpipes, are to be formed. The light openings 603 are disposed in thefunctioning side, as shown in FIG. 6. In alternative embodiments, a setof conically or parabolically shaped cores or a set of rectangular,circular or other shaped dam-bars are provided. For instance, when theparabolically shaped cores are utilized, the light openings 603 aremolded into parabolic shapes that produce consistent light beams.

In one aspect of the preferred embodiment, the lamp tile has a flatpanel shape. In alternative embodiment, the functioning side of lamptile 601 may be concave, convex or sloped in one direction in order toaccommodate different display board designs.

Referring to FIG. 7, a light opening 603 exposes portions of a pair ofanode leads 211 and a corresponding node 117 of the cathode leads 119.When light lamps 651 are disposed in the light openings 603, the cathodeend of each lamp 651 makes a contact with a corresponding exposedportion of the cathode node 117, and the anode end of each lamp makes acontact with corresponding exposed portion of anode lead 211.

The contacts between ends of a light lamp and exposed portions of theleads are, preferably, established by a wire bonding process. In thewire bonding process, thin wires 653 are provided to establish theelectrical connections. Subsequently, the light opening is, preferably,filled with clear epoxy material and, alternatively, is not filled withany material.

The anode and cathode leads function as switches for the inserted lightlamps. In other words, one combination of an anode and a cathodefunction as one switch and the other combination functions as a secondswitch.

In one of the preferred embodiments, the inserted light lamps arecapable of displaying three different colors: green, red and white. Thisis achieved by providing two different colored lamps, green and red,into each of the light openings. The on/off states of each the lamp iscontrolled by the pair of anodes and cathodes switches. Morespecifically, one anode and cathode combination controls the on/offstates of green colored lamp and the other combination controls theon/off states of red colored lamp. Furthermore, when both of them are inthe on state, then the resulting light beam is the white color.

In an alternative embodiment, single color light lamps are utilized. Inthis embodiment, its anode leads do not need to be paired up asdescribed by referencing FIGS. 1 and 2, since only one combination of ananode and cathode leads are required. Furthermore, when the size andshape of light lamps change, the size and shape of the nodes of cathodeleads and light openings change as well to accommodate different lightlamps.

In the embodiment depicted in FIG. 6, each lamp tile is provided withsixteen sets of switches, each set with two switches. Each switch iscontrolled by supplying electrical power to or cutting off theelectrical power from corresponding lead ends extending beyond themolding material of the corresponding lamp tile. For instance, a lightopening 609 exposes a portion of a node of cathode lead 611 which hastwo ends extending outside of the molded body and a portion of a pair ofanode leads 613 and 615 each of which has one end. Therefore, in thepreceding configuration, a lamp inserted into the light opening 609, itsanode and cathode ends electrically connected to the corresponding anodeleads 613, 615 and cathode lead 611, is controlled by supplyingelectrical power to or cutting off the power to respective lead ends. Inthe similar manner, all of the inserted light lamps are switched on oroff.

In other alternative embodiments, the resulting light opening array canbe different from a four by four array since a simple change in thestructure of the lead frames can allow the resulting tile to have anysize array-including a non square array as described above in referencewith FIG. 1.

Referring back to FIG. 3, the trimmer cuts individual lamp tiles fromthe respective tiles by trimming the connecting members 123 and 215 fromrespective leads connected to them.

In one aspect of the preferred embodiment, both ends of each cathode andanode leads protrude from respective lamp tiles. In other words, eachcathode lead starts from one side of the lamp tile, extends across thelamp tile, and protrude from the other side of the lamp tile. Each anodelead also starts and ends on opposite sides of the respective lamp tile.In alternative embodiment, not all of the anode and cathode leads extendthe length of the respective lamp tiles.

In another aspect of the preferred embodiment, when the trimmer 311 cutsthe connecting members 123 and 215, each cathode lead has two ends,whereas each anode lead has only one end. In alternative embodiments,two ends are provided for each anode lead or only one end provided foreach cathode lead. In any event, the ends of leads which protrude fromthe lamp tiles are bent downward to be inserted into a display board.

The novel design of the cathode and anode lead frames 101 and 201 ofthis invention allows the above described assembly line processing to beachieved. This assembly line processing further allows the subsequentpost processing to take place. Hence, in the preferred embodiment thetrimmed lamp tiles remain in the reels for further processing. Inanother embodiment, however, the trimmed lamp tiles are separated fromthe reels and stored for further processing.

Subsequent to the trimmer, the post processor performs a number ofpackaging functions on the lamp tiles. The packaging functions include acombination of inserting light lamps into the light openings 320, wirebonding 321, inserting clear epoxy into the light openings 323. The wirebonding process employs thin wires, preferably made from aluminum, toconnect the exposed portions of the anode and cathode leads torespective anode and cathode ends of inserted lamps. The testing process325 tests the integrity of lamp tiles such as non-conductivity betweenthe anode and cathode leads and on/off states of the inserted lightlamps.

After the post processing, the lamp tiles are ready to be mounted into adisplay board that is adapted to receive the lamp tiles and wired tocontrol the lamp tiles and respective lamps.

One of ordinary skill in the art can envision numerous variations andmodifications. For example, the cathode reel feeding holes 111 and thealignment holes 113 can be located at different positions, or thecathode lead frame 101 can be overlaid on top of anode lead frame 201.All of these modifications are contemplated by the true spirit and scopeof the following claims.

What is claimed is:
 1. A method of fabricating at least one molded bodyhaving a plurality of electrically conductive leads protrudingtherefrom, said method including the steps of: providing a first leadframe segment defining a first aperture and including at least one firstlead extending into said first lead frame aperture; providing a secondlead frame segment defining a second aperture and including at least onesecond lead extending into said second lead frame aperture; overlayingsaid first and second lead frame segments above the other such that saidfirst and second leads form an intersection in a plan view of saidoverlaid lead frame segments, and said first and second leads are spacedapart from each other at said intersection by a predetermined distancein a side view of said overlaid lead frame segments; and depositingmolding material in a predetermined pattern on said intersection,thereby forming said molded body wherein a portion of said first leadprotrudes from said deposited molding material, and a portion of saidsecond lead protrudes from said deposited molding material.
 2. A methodaccording to claim 1, which further comprises forming an opening oversaid intersection exposing portions of said first and second leads. 3.The method of claim 1, which further comprises trimming said first andsecond leads from said first and second lead frame segments.
 4. Themethod of claim 1, wherein said step of overlaying said first and secondleads includes the step of setting said predetermined distance to bebetween about 0.01 and 0.03 inches.
 5. The method of claim 1, whereinsaid step of depositing said molding material includes the step ofselecting said molding material to be a high temperature nylon which iscapable of withstanding temperatures up to 570° F.
 6. A method offabricating a plurality of molded bodies having electrically conductiveleads protruding therefrom, said method including the steps of:providing a plurality of first lead frame segments which define firstapertures and include a plurality of first leads extending into saidfirst lead frame apertures; providing a plurality of second lead framesegments which define second apertures and include a plurality of secondleads extending into said second lead frame apertures; overlaying one ofsaid first and second lead frame segments above the other such thatcorresponding said first and second leads form an array of intersectionsin a plan view of said overlaid lead frame segments, and are spacedapart from each other at each said intersection by a predetermineddistance in a side view of said overlaid lead frame segments; anddepositing molding material in a predetermined pattern on a plurality ofsaid intersections, thereby forming a molded body wherein a portion ofeach corresponding said first lead protrudes from said deposited moldingmaterial, and a portion of each corresponding said second lead protrudesfrom said deposited molding material.
 7. A method of claim 6, whichfurther comprises forming a plurality of openings over said plurality ofintersections exposing portions of corresponding said first and secondleads.
 8. The method of claim 6, further comprising the step of trimmingsaid corresponding first and second leads from said respective leadframe segments.
 9. The method of claim 6, wherein said step ofpositioning said first and second leads includes the step of settingsaid predetermined distance to be between about 0.01 and 0.03 inches.10. The method of claim 6, wherein said step of positioning said firstand second leads includes the step of setting said predetermineddistance to be between about 0.01 and 0.015 inches.
 11. The method ofclaim 6, wherein said first frames segment are produced by the step ofstamping said first lead frame segments on a first elongated sheet madeof electrically conductive rigid material, and said second framesegments are made by the step of stamping said second lead framesegments on a second elongated sheet made of electrically conductiverigid material.
 12. The method of claim 6, wherein said step ofdepositing said molding material, includes the step of selecting saidmolding material to be a high temperature nylon which is capable ofwithstanding temperatures up to 570° F.
 13. The method of claim 6, whichfurther includes the step of depositing epoxy material between first andsecond leads over said intersections.
 14. The method of claim 1, whereinthe step of overlaying said first and second lead frame segmentsincludes the step of arranging said first and second lead frame segmentsso that said first and the second leads intersect substantiallyperpendicular to each other.
 15. The method of claim 6, wherein the stepof overlaying said first and second lead frame segments includes thestep of arranging said first and second lead frame segments so that saidfirst and the second leads intersect substantially perpendicular to eachother.